Gray-level reducing-based text image coding

In this paper, a novel compression method on text image, called a gray-level reducing-based text image coding method (GRTIC), is proposed. The characteristic of text image is analyzed, and not the traditional binary mode but gray-level mode is needed in text image coder at low-resolution to recognize the characters. Furthermore, in gray-level text image coder, just a few gray levels are needed to recognize one character. So the original text image is first gray-level reduced, and then an adaptive arithmetic coder is applied. At the same PSNR, GRTIC can get more compression efficiency than JPEG or JPEG2000.